Telephone system



Dec. 4, 1928. 1,693,824

M. B. STAZAK TELEPHONE SYSTEM Filed May 10, 1926 3 Sheets-Sheet 1 217m ZYz'icimelfifiiazak .357 J.a. MM.

Dec. 4, 1928.

, M. B. STAZAK TELEPHONE SYSTEM Filed May 10, 1926 :s Sheets-Sheet 2 2271 72 27? MIL-225225 5257M.

Dec. 4, 1928. 1,693,824

M. B. STAZAK TELEPHONE SYSTEM Filguav lo mas u: I set 3 Pa ten ted Dec. 4, 192 8. UNIT-ED S'T'A MICHAEL; .15: s rAzAm, 01'3 CHICAGO;

PATENT OFFICE-.1.

. 1| 31.1 .vi 35,1- l.. A; H mi. N ":n ILLINOIS; ASSIQIEOR 110.. KELL GG $WITGEBOARD' AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILIIINQIS'.

, niziiii'iiSP'Jl' ex; TELEPHONE SYSTEM.

its objects the ,provi'sion jof; a ni imfir oy eling tr unkj 120. 11a called fo subscfibersj 'lccal teleph o ne liiie, the si gnzplling of called 61 subscriber; lthough set" the f opeif ato rof the tell siiiitchirig :t'r' mk otlap plie'd to' the called line by ,h'er, huh ontijolled by the operatp whb actuates means to extend the r n i sc i'i'e fc il nd .L y' the t l sWit-chijn-gfifmiink gpergi hbr ti) the called line;

. Anqtliei' feat iir e 'pf myiilwei tiqn the provision Of; a .hn'iv'eis'el ,tcll switchiii 'trui k which when use fissocia tid With a t oll cord] circuit may extend; gnbtik s ffomj toll line thrbilgli the medii fllof thje hliiv ers'zi l toll switchingjtruril te -71. a ijehbbc cciiii ic' i bat'te'ry lpcal lines wrminapmg at a'univer'sal ldcal switc hlioa i'd l h ThefnbcVe feature as ellies; othefs'f ne't specifically pointed iq'fit ivill bejmdi e fully scigibed in; the, eij suniglspecifica qibn :z rid the alppn dd Tclai i s. To more cleai'ly 1: njfle standthe sz i'ine; 'referen e. may be hadito the tors p s twn id whic 29 131 9 a SW' X: ingr n11] mAP snide calling plug glifcofinected bv thcheavily muf'ked congluctoifs: The-loll cbrcl @iieuit can beused fer counselin dir'ee wgnather tensgbsm-i lys iiileor tii aitbl'l switching tifurik circuit such 'as-is illhs 00rd circuit C comprises 2 ringb ck key RB which Wheil actuated j connects the; gc'ne ratiii to firing "afc'allii'ig" "toll subscriber as is Well kiicwiijiri the are. A li'steg iiig'key LK is pifbyiclefl which when actuated connects" the 1 Qpeiizihdfis set 0 iii circuit with the cord c'cnductcfs t6 place herself incdmih'li licaltidii with, the czflliiigftoll subscri er; POlzifizd relty PR, adi's'co n nejctconti ol re lzily DCR ringhig generator G to *s' gnazi a' allu sue.

m-mflis-De'rid' E unwa hed mangeas "will be more fiill'y'; hereir'idfiei? described;

A ri n "com -51 lamp sig iiztl j is 'al'so associated with the celliiig e' r'ld of the toll Oilfl'lill'ltliG subserimr I chief. call c l i gi pwec ni e tc *a t ll swilichifl l. TcRlcontrbls the the calling end of thetrunli is energized when the plug TP is connected to a called line as just described to efl'ace the signal TS. The sleeve relay SL in association with the relay TCR provides means for signalling the operator of the toll cord C through the agency of a ringing control lamp RCL that she may now operate the ringing key BK ofthe cord C to operate means including a ringing relay ER in the trunk D to connect ringing current to the called line, 1 The operator of the trunk D is equipped with a party line ring key RK' and itsassociated frequency generators G and the operator of the trunk D selects the proper ringinggenerator frequency through the agency of the party line ringinglkey RK but does not connect the ringing current to the called line as will be hereinafterdescribed. The relay RR of the trunk fl) when operated by current from the generator G of the toll cord C of Fig, 1 causes the operation of a ringing control relay RGR which nowconnects the frequency 'selectedby the operator to the called line.

A calling supervisory relay SB int-he trunk D operates when the called for substation answers and; prevents further application of ringing current on the called line; A- reversing keyRV also associated with the trunk Dior reversing the application of ringing current from the tip to ring conductors of the trunk D and vice-versa as done in ringing called subscribers on aten party line in which live ofthe substations are connected for ringi ing purposes to, the tip conductor and the other five to the ring conductor and thenee' to ground. 'When ringing the subscribers con 7 nected to the ring conductor the key RV is left undisturbed; c When ringing thos efsub stations in which the ringer is connected from the tip conductor-to ground the keyRV is operated; 7 Thus only five ringing generators are necessary to operate the harmonic-'ring-j 'ers oft-he subscribers on the ten partyiline.

To the right of Fig. 2, I illustrate a called substation F terminating at the exchange 7 into a line'circuit L comprising a cut oif reo layCO aliue'rela- LR, and the multiplejac s J a line signal S Referring now to Fig. 3I 'illustrate an other toll switching trunk circuit E which is adapted to'operate in connection with the toll.

cord circuit C. :Fig. 3 when placed to the right of Fig. 1 illustrates a complete system c and 'operatesin association with a universal system inwhich common battery and magneto lines: tern'iinate" at a universal local switchboard, The universal toll switching trunk circuit E comprises a trunk signal controllrelay TCR which is energized when the I operatorofthe tollcord circuit (linser'ts the calling plug G]? into the trunk jack TJ leading to thetrunk E. A trunk signal TS associated with the relayTCR is provided "for A, ringing relay RR is the 'usual purposes.

through the j lnedium of the toll trunk Das'illustratedin Fig. 2. Fora clear crates is applied operated when ringingcurrentis ap lied to the trunk E by the tolloperator of t e cord C when connectionis established with a called l common battery line but does not operate when r1ngrngcurrent-1s extended to a'called magneto line.

" A ringing lockout relay RLR isprovided and operates when a called common battery 1 subscriber answers to prevent further ap- 'plication of ringing currentto the called line.

A repeating coil switchingrelay RSVV is provided whichcontrols the connection ofthe re;

peating coil RC depending on whether aconf nection is established with a called conn'non battery linc or a called magneto linef The outgoing end of the trunk IE providedwith a'trunk plug TP whereby connection may be established witheit-her a common'battery line or a magneto line and is also provided with a pair of sleeve relays SLand" SL and switching relay SW and asupervisory relay SR; To the right "of Fig. I illustrate a circuit L? which comline fromthesubstation A of Fig. 1 and which is to be extended to acommon battery called subscriber common battery "exchange switchboard switching understanding of this connection Fig! is placed to the right of Fig.- land assuming that, the toll subscriber atsubstatiOnr A; op hishan Ll generator whereupon current to the line to opgpratc theline re-i energizes to atthe latching lay LR. Theline relayL tract its armature? to permit spring 3 to lock 7 position and the movjenientlof thelatching spring 3 closes a circuitfor theline signal S from battery through thelamp S to ground at alternatefcontact l of the latching spring 3; In response to this signal the toll operator .atQ insertsthe answering plug AP into the jack J of the calling linolA to close an energizing circuit for the cut oiffrelay C0 of i the line circuit L traced from battery through F terminating .at a local I has no i

the armaturefl in its actuated the sleeve contacts of theconnected plug AP 1 and jack J toground through the winding of relay CO. Relay ICO causes thelatching spring 3 of relay LE to be raised to permit the armature 2 to fallback to again'open thealternate contact 4 of the relay LR 'toeflace the line signal S. The operator now actuates her listening keyLK to connect her operators set 0 to inqui re the-wants of the cali.

, the toll'op'erato'r C that'is assigned; the op the sleeve centjacte o'ftheglcbhheeted lug'CP RK to cop nect the prpper r lngmg frequency to the called li eand ass ul ljlhg that the gen erzgtor Gr is the ne'selec trol of the tol llopel atqf zit Q asffwill newfbe described. The opeizitdr etD hfav inghin called line nienergizi cifcuit' ie etabh ed for the sleeve relay an fd thelclit 01f; relay co -m line ir uie hg'q thefcqlled line traced from hatteryithletigh the 'f relaySL, eoh diictoif 14, s l'eefiie eohtziet's' o ffthe cennected fphig TB and j ac kf' J to lgi euf d through the yviridii 'gpf lelay Q0, tl'ielzt'ttel' relay ope mtihgglearjthe lihefcenclueitdifs thi'pijgh the iiiidi'nge 8, and 9 is desired to be ztppli edt o the I This low i'esistgin'ce path just described shun'te the highir'eeis'mne Wihdih'g 9 of rela TORehdipei hlits the eigna't RCL t light infdibating' to the "toll operater at C thiit t l'le trunk opem'tifdf the tfuhk D lms established m ct mn ectien with; theWimted cellechlin'e at F and thutjringm g current may'now bedlfi Selected gene'r zitofG j te the called lil'ie mid plunger, eondfic'itor 2 7," 01-1m1*Contact of 26 en my RG11;1-in jcp1itaets of the cri; necte'd plug TP and'jaek J tlneugh, thee-all bell a tthe celled EiflbSttttiClhF b h the tip pentacts of theeolinectedfjz e i J and key ILK, conductor. 38, alternate contact37 nate contacts 26 and 31 to connect the generator G which was selected by theoperator of the trunk D.

the lamp RCL aspreviously described.

When the called subscriberat the substation F responds in answertohisccall signal the removal of his receiver closes an energizing circuit for the supervisory "relay SR traced from battery through the winding 34 of relay SR, winding 0 of the repeating coil RC, normal contact 26 of relay RCR which relay deenergized after each. application ot'.1"inging currentgrin r contacts of the connected plug T1? and jack J, the now closed contacts oi? the substation switch hook at F, back through the tip contacts of the jack J and plug flP, alternate contactBO of relay SL,

windingcl of the repeating: coil BC to ground through the winding3'5 of. relay SR. The relay SR upon energiiaation opens ts normal contact Q l which prevents the energization ot' the relay BCR should the relay RR be energized by ringing current after the called subscriber answers so as to prevent turther application of ringing current after the subscriber at the called substation F hasanswered. The relay SR upon energization opens its normal contact 18 and opens the low resistance path through the winding-S of the relay TOR andfthe circuit for relay 'TGR i now extends from ground through the high and loW windings 9 and 8 to battery through The lamp RCL is again effacedto. notifyfthe toll operator at C that the called subscriber at F has answered. The calling toll subscriber at A and the called subscriber at F are now in a conversational circuitwhich may be traced. over the heavily marked conductors.

. When conversation is terminated the subscriber at the substation F replaces hisrcceiver to aga n open the circuit of-therelay SR andthe relaydeenergizing the closure of its normal .contaet lSzagarn.closes thelow resistance path through the winding Slot the relay TCR to permit the lamp RCL to again Cit erat-or to causethe the clos ng of its alternate contact 36 closes an energizing circuit for the disconnect con- I light tonotify the toll operator at O that the called subscriber at F has replaced his receiver. The toll subscriber at A also re places his receiver relay PR to operate and trol relayDCR traced ['roi'u battery through the relay DCR to ground at altcriiiate contact 360i relay PR. The closure of alternate contact 37 of the relay DCR closesalocking cir cuit for the said relayDCR- traced from battery through relay DCR alternate contact 37, conductor 38 to ground at normal contact 39 ot the listening keylLK. y

The closure of alternate contact 37 s also closes a circuit for the clearing out gnal COS traced from ground at normal contact .39 of from "the jack J al the normal normal contact 31 of relay RCR,

relay SL.

and operates his hand ene.

ol. relay DCR, through the lamp to battery. The clearing out signal COS is lighted by .currentfimving over this circuitand no tilies the operatorat C that the calling toll subscriber-at Alias also replaced his receiver; The tolloperator notinv the two lighted signals COS and RCL withdraws tlieplugs AP and CP from the respective acksc J aiidTJ. The plug when disconnected ows. the out off relay CO to restore and the operator of C'also momentarily operates the listening key LK to open contact 39to open thecircuit ofto efl'a'ce theqsig'nal COS. The

crater has disconnected the plug, GP from the jack TJ. Withdraws the plug open the circuitof relay and the cutoffrelay C0 of theline circuit L of the called liner Relay SL restoring, its alternate eont-act'42 is opened to efiacethe signal TS. The apparatus used in estab SL of the trunk D The lamp TS is lighted andnotifies the trunk operator at D that thetoll op 'The trunk operator at D now lishing the connection just described is now at normal and. available for [establishing other connections. a p 3 c Having described in detail the operation of Fig, 1 in connection with thetoll switch;

ing trunk circuit as illust-ratedin Fig. 2 I

will now describe the operation of the tell i cord circuit C of;Fig.i1 in connection with Fig. 3 wl1ichfillustrates a universal -toll switching trunk circuit E whiohmay be used c for extending a. connection from the tollsubstation battery substation N or magneto substation M as called lines and asillustrated in Fig. 3.

Assumingthatithe toll subscriber at'A initiates 'a call and .desiresto be placed in com munication withl the o'ornmonbattery sub i the same up to and including the time that station N the operation of the toll cord G is of Fig. 1 with either the common! the calling plug CPis inserted into the trunk jack TJ assigned by the trunkopittor 0 of trunk E leading t the n switching trunk circuit The insertion of the plug GP into the trunk jack TJ closes a circuit for the relay TOR battery: k TOR Ito operate but due to the high-resistigo y ofthe universal trunkQE traced through the lampRCIrto as before described to allow relay ance Winding 45 of relay @TCRf the damp RCL does" not light for, reasons as before describech The relay TOR crating. itsalternate contact 46 is plosed an cio upl' circuit tor the trunk signal TS relay RR failing to energize relay RSlV ie the low resistance pathfor the lamp RCL at mains at normal and it is thus readily apparent that ringing current cannot be transmitted tothe called line after the subscriber thereat has removed his receiver.

The opening of normal contact SB 'upon energization ofthat relay opens thetoll. cord C through the low resistance winding f the relay, TCR and the high resistance path for lamp RCL is again closed through the high and low windings 45 and of relayTCR to ground to again efl'ace the lamp RCL to notify the toll operator at C that the called subscriber at the substation N has answered. The relay RSVV being deenergized its normal contactsmfl 1, 72 and 73 are again closed to again connect the wind ings aflb" and c cl of the repeating coil RC across the respective tip and ring conductors of the trunkE and the talkingcircuit between the calling toll subscriber at A and the called subscriber at N may be traced over the heavily marked conductors including the windings a, b, 0' and d of the repeating coilltc.

1 When conversation has terminated the subscribers replace their receivers upon their respective switchhooks1 and the replacing of the receiver at the toll substation A is thesame as previously described in connection with Figs. 1 and 2. The replacing the receiver at the called substation Nagain opens theen ergiz-ing circuit of relay SR and the closing of its normalcontact 57 again closes the 'iow resistance path through the w nding 55 of relay TCR' for thela'mp RCL of the tollici'rcuit G and thelamp RCL lighting gives the toll operatorat-C a visual indication that the called subscriber at has replacedhisre- "ceiver. The toll operator at C noting the two lighted signals COS and RCL withdraws the respective plugs APand C P from the respective jacks J and TJ and operates her lis toning ire-y LK momentarily to elface the signal COS and the-withdrawal of the plug GP from the jack TJ efi'acles the signal RCL.

The relay TCRof the trunk E restores when the disconnection of the plugCP from the j ack TJ takes place and the closing of'its norm'alfcontactlfi closes a circuit for the lamp TS to ground at alternate contact 48 of rela-YISW Over conductor 60. The lighting of the lamp TS indicates to the trunk operator at E that the toll operator at C hasdisconnected and shenow withdraws the plug TP from the jack J 2 of the called line permitting relays SL' and SL to restore and the relay SL restoring its alternate contact 53 is opened to allow the relay SW to restore and the opening its alternate contact 48 opens the locking circuit of the relav RLR and the relay restores. The cut off relay CO oi the line circuit L associated with the called line N also restores when the plug TP is disconnected and theapparatus used in establishts-3st;

ing a connection between the toll subscriber at A of 1 and the called common battery subscriber at N ofv Fig." 3 is now at normal and available for establishing other connec l tio'ns. 57 ofrelay I will now describe how a connection is estahlished between the calling toll substation Aof Fig. 1 and the called magneto substa tion l igg3througli the agency of the toll cord C'of Fig. land the universal toll switcl'iing trunk E of 3. The operation of the apparatus is the same as just described up to and including thepoint of operationof the relay TOR of the trunk B when the plug -c OP is inserted into the trunk jack TJ leading to trunk E to light the lam TC, of the trunk E to notifythe operator t ml: the toll opera-I tor of C hasconnected to the assigned trunk jack as beforedescribed The trunlc operator at E tests the called magneto line .M "in the usual. manner and finding it idleinserts the plug TP' jntothejack JTof the called line.

Thisinsertionfbrings about the o eration, of

to open normal contacts 80 and 81 to pre pare the-line for ringing and talking purposes. The relay SL operating closes a circuit fort-he relay SW to groundat alternate contact,53 ofrelaySLand the opening of normal-contact 48 of the relay SW opens the circuit for the signal TS and thelamp TS is effacedi The closureof alternate contact 48 of relay SlVjalso closes a circuit'for the relay RSW traced from battery, through the winding ofrelay RSW, conductors 68 and- 69, normal contact58 of the relay SL conduc-tors 59 and 60 to ground at alternate contact 48 of relay y The relay R-SWoperates over this circuit and remains energized as long as theplug TPf remains in the jack J 3 of the called. line, and the opening of its normal contacts 70, 71, T2, and 73disconnects the windings 0:, b" and c and d ofthe repeat ing coil RC from the tip and ring con ductors o'f the trunk E.

The relay SL having failed to energize as i r before described no lowresistztnc path for "the lamp RCL of the toll cord C is closed 1 through the winding ofrelay TCR and the tolloperator at C does n,otreceive a-visual in dication to notify her that the trunk operator has inserted the :plug TP into the jack J of the called magneto line M. The lamp RGL 1does not light due'to the circuitfextending through the low resistance and high resistandpl it: GP; normal contact 21 of the ringing key'RKof the toll cordC, throughthe Windtacts of the connected plug CPLmiclaafclcHJ,

fance'ii indings 55 and of. the relay TGR "'tofgroiiiid.

"Theltoll operatorat c' actu'ates the rin ing key'RK to. {connect ringing current from the generator" G tothe' called magneto substation M, f and this ringing current may he plug contact -73 of the "tii'ball he'll at the called suh J alternate contact alternate*contact 70 ot GP, to ground *at" alternate contact .21

is naled: tl1e toll operator at C actuates the li; feni'ng "l'r ey DICE-from time to time t'o listenfiinfor supervision; lVhcnthc 'suhs criher at the called substation lift aiis'ivers the "subscriber thfereat "andi the sijlhscrihcr at the toll substation-are in conversational i circuit which may teamed over the h e'avily marketl conductors.

lVhe n' thefsiibs'crihers at 'A an drM have finr 'ished their conversation they replace their receivers upon their respective switchlio'olrs.

After thesuhscriber atlt'he called substation J M has replaced lii s'recei'ver he operates the hand generator atthe 'sub'stationainl current therefrom nextntl's tromf one side of the hand generatorthereatjthrough the tip contacts of the plug TP 'andfi'ackd falternate contact '74" of 1'- layISWV,alternate;contaCtWO' of relay RSWV, tip contactsof thelconnectcd iack'TJ in'gs' "of he relayPR back throu ih normal contact of therni m key R-Kl ring con alternate contact (if relay-"RSYV, 19mg c0n- 'tacts' of the connected plug ll l? and jack J to'the otlier neto Sammie-11M:

f The relay'PR operating; its alternate C1011- tactf36 i's closed therehy'closing ac'irciiit for the relay thetoll cord and'the rela'v DCR energizing closesits alternate conta e-1 37 to close a locking circuit foritself'to groundiat normal contact '39 "of-the listening key; LK. The closin'g'of alternate contact '37 also'closes a circuit for the lamp lCOSto ground at contact j39ot1the listening key UK.

The i p 'll ei theluglitfitiljdlscoldto said trunk a telephoneline, said plug connect signal COS new removes the plug GP. from the jack TH which opens the circuit of relay TOR of the trunlrE. The relay TCR deenergizing, its normal contact 46 is closed. to close a'circuit for IlIGdFLhQPITS traced fron'i' l')attery, tlirough the non" normal [contact 4:6;Qf relay 'TGR,conductor 60 to groundatalternate Contact 48'o f 1"elay SN. The lighted signal TS" notifiesthe operator "of tr-unk'Ethat the toll operator has with drawn the plug GP from the jaclr' TJ; The

trunk operatorat EnoW ithdraws the plug T1 from the jack J Whicl1 allo s the relay 1 SL" ofthe'trunk E andthecutotl' relay CO 'of the line circu t L oft-he called l ne to de- Q' opensihe z energize. llierelay SL rcstorin I energizing circuitofrclay'SiV' and-there 'SlV" restori ng efiiace's the signal TS and '0 the energizing circuit of relziyli'SWV. 'l he "Should the calling tell subscriber-atA- he the first 'tooper'ate'liis hand gene "ator after replacing his recei-ver,-tl ie cni rent therefrom will 'oper ate the relay PR of C, to operate re --lay DG-Rtelight the lamp COSandthe distonnectionef the established cen-nectionfrom this ;'point on isthe samcas just d'es'cribed.

While I have illustrated and-{described a prelEerred zeml'io'diin'ent of my invention... it is to be nnders toed that I do notvwish to be limited to the embodiment ce'ntained inmthe s ieciticatien, my invention mayibe readspirit of the invention. Having described my invention What-I claim-as no it "Patentis: a; i "1. In a telephone a system, an operators cordcircuit, a plug ended-trunkcircuit at anothei eperators position, connection means fors'a-id cordandtrunk for connectingsai'd cordto said trunk, a tel'ephoneline'; said plug vendedtrunlcadapted to be connected to said line, 1'i1igi11g current means "for said trunk,

} setby the trunk operator but-not connected s de'fof the generator the many, to sa dlin'e, said application at rmgingcnri v 2. In 'a telephone system, an operators cord circuit, aplugaended trnnkcircuit at another operators position, connection means "for said cer d'and trunk for connecting said ended trunk adapted'to be connected to said a line ringing'current means ior said trunk set by the trunk operator but not connected to said line, m'eansitor said cord circuit actua'ted hy said operator of said cordcircuit. to operate means in saidtrunk to connect said ringingc nrrent means set by said trunkoperator'tothe called lin'e, 'and means in said trunk circuit controlled over said telephone used in establisl'iing the con Ji y applied in many diiierent ways and varrone purposes" ithout departmg" from the anedesireto secure by Letters line for discontinuing the applicationofringmg current to the called line.

3. In a telephone system, an operators cord circuit, a plug ended trunk circuit atanother operators position, a jack for said plug ended trunk adapted to be connected by a plug from said cordcircuit, a telephone line, said plug endof said trunk adapted to be connected to said line, ringing current means for said trunk set by the trunkoperator but not connected to said line, generator means for said cord and means in said cord operated to connect said generator means to said trunk, to operate means therein to connect the ringing current means set by said trunk operator to Y said telophon e 1111c, and means cont-rolled over said telephone line {or rendering inoperative the means for connectingsaid ringing current means to the said telephone line.

i 4. In a telephone system, an operatorls cord circuit, a plug ended trunk circuit-at another operators position, connection means for said cord and trunk for connecting said cord to vsaid trunk, a telephone line, said plug ended -,trunk adapted to be connected to said telephone line, ringing current means for said trunk set by the trunk operator but not connected to said line, generator ineans forsaid cord circuit, a ringing relay for said trunk,

means for said cord'actuated to connect said generator means to'said trunk to operate said ringing relay to operate'switching meansin said trunk to connect said ringing current means set by said trunk operator to said telephone line, and means controlled over said V erators position, said plug ended trunk cord and trunk for connecting said cord tosaid trunk, a telephone line,connection means for connecting said trunk to said line, ringing means in said trunk adapted to be set by the 7 adapted to be connected to said'telephone line, ringmgcurrent means for said trunk set by the trunk operator but not connected tosard line, generator means for said cord circuit, a ringing relay and a second relay for said trunl'z, means for-said cord actuated to. connect said generator means to said trunk to operate said ringing relay, said ringing relay operating said second relay to connect said ringing current means set by said trunk operator to said telephone line, and means conj trolled over said telephone line tor-preventing the operation ot saidsecond relay thereby preventing the further application of ringing current to the said line. Y i

6. In a telephone system, an operators cord circuit, aplug ended trunk circuitat another operators position, connection means for said trunk operator but not connected to said line, a

operator controlled meansjin saidPc ord solely affecting said ringing means toconnect r ngmg currentvto said line, means 1n said trunk circuit controlled over said line for prevent mg the appl cation of said'currentto said line, a relay for saidtrnnk provided, within high and low winding and a signal for said cord, said relay preventing the operation of said signalwhen said cord is connected to said trunk to give the operator of said cord an indication of a certain condition of said trunk. v I I 1 ,7. In atelephone system, an operators cord circuit, aplug ended trunk circuit at another} operators position, connection means for said cord and trunk for connecting said cordlto said trunk, a telephone line terminating at said other operators position, a relay forsaid trunk rovided with a high resistance wind- 7 ing an a low resistance Winding anda 'signal for said cord, said rela preventing the operationof said signalvv en ;.saidcord is connected to said trunk to give the operator of said cord an indicationof one condition of said trunk, means in said trunk o erated upon the connection of said trunk with said telephone line to affect said relay to permittlie operation of said signal to givethe'operator of said cord an indication ofanother condition of said trunk, and means in said trunk controlled over said telephone line adapted to affect said rela to give an indicationof a third condition '0 said trunk. 3 I I a 8; In a telephone system, an operators cord circuit, a plug ended trunk circuit atanother operators position, connection means for said cord, and trunk circuit for connecting said cord to said trunk, telephone lines of different character terminating at said other operators position, said plug" ended trunk adapted tobe connected to the said lines of different character and ringing I current means iorjsaid cord circuit adapted jto be connected to said'lines through said trunk and solely under the control of theoperator of saidcord, and meansfiin said trunk controlled over one type of said lines for preventing theconnection or connected line. a, a y A r a 9; In a telephone system, an operators cord ringing current to said circuit, a plug ended trunk circuit at another operatofls position, connection means fOI SBJd cord and trunk for connectin said cord to said trunk, telephonellnes of different character terminating at said other oper ators position, said plug ended trunk adapted to be connected to said lines' 'of different character, a relay for said trunk provided with a high resistance Winding and a low resistance winding, a si mail for. saidflcord, sald relay bemg connected in ser eswlth said signal when said cord is connected to sa d trunkto-afie'ctsaid signal of said cord to give the operator ofthe cord anindicjation of a certain character and means operated when sald trunk is connected to a line of a certain character to, shunt out the high resistance Windingof said relay to permit the operation of said signal to give the operator of the cord an indication of another condition of said trunk, and means controlled over said line for opening said shunt circuit whereby said signal is again placed in a series connection with said high and low resistance windings of said relay to give the operator of the cord an'indication of a third condition of said trunk.

10, In a telephone system, an operators cord circuit, a plug ended trunk circuit at another operators position, connection means for said cord and trunk for connecting said cord to said trunk, telephone lines of different character terminating at said other operators position, said plug ended trunk adapted to be connected to said lines of different character,

a relay for said trunk provided with a high resistance and low resistance Winding, a sig'-' nal for said cord, said relay operating windings being connected in series with said signalwhen said cord is connected to said trunk to aflec'tsaid signal of said cord, to give the operator of the cord an indication of a certain character and means operated when said trunkis connected to a lineof certain character to shunt said high resistance Winding of said relay out of said series connection to permit the operation of said, signal, to give the operator of said cord'an indication of another condition of said trunk, said means in said trunk only partially operative when said trunk is'connected to a line ofanot-her char actor to prevent said relay from affecting said signal, and means in said trunk controlled over a lineof said first character for opening said shunt circuit to again connect said signal in series with said high and low resist ance'winding's whereby an indication of a third'condition of said trunk is given to the cord operator.

In testimony whereof I have signed this I specification;

MICHAEL B. STAZAK 

